Continuous tank furnace



Aug. 24 1926. 1,597,440

E. T. FERNGREN CONTINUOUS TANK FURNAC'n` Filed March 2,!1923 3Sheets-Sheet 1 7/"66/7 ggg as long a :period asin theldead ,cornersofn 1Patentedv ng. v1926.

'l 4u Nrralui-7s"rn-'lues Enoes: Tjrnauensu', or, Tomzno, omo, Lesiones.To TnnmnnYowxn anni: @nnss eourm,"er Towne, oma-'n conronanou or ome.

eoNTINu'ous TANK renuncia' Apparat-1mi met men 2, 1923.v ser-m1 u.$22,270.

. This invention relates to a continuous a furnace designed' to supplymolten glass 1 -to a sheet-glass drawing machine. While 6 the furnacewas primarily designed for use with ay sheet drawing apparatus of thetype setforth in the patent to Colburn, 1,248,809,"

' 'granted Dec. 4, 1917 ,itwill be equallyfuse ful with othertypes ofsheet drawing maf 10 chinos where the sheet is drawn vertically form apool of molten glass. A The furnaces new in general use with .this typeAof machine 4comprise tanks of a generally rectangular' shape which.contain a large reservoirof molten glass. This molten glass iows slowlythrough 'the `tank from a melting chamber at' one end to. the draw-potat'the 'other `end from which the k glass sheet is drawn upwardly. Aconsider-'- able; portion of the molten 'glasswill lie ract1cally, undisturbed or' stagnant lin the' deadv corners of the tank, and this .glassvgradually changes in temperature and comtoward and into the'drawpot.This stagnant glass leads to the formation of devitrilied glass'. orso-called dog-metal, in the draw-pot and even in the sides of the chan--nel leading 'into the draw-pot where the movement ofthe glass issluggish 'as compared to' the movement in the channel,

These variations in the composition of the molten glass, together. withthe resulting differences in the tractive 'response of the Vglass 4as itis drawn along ,toward and into the sheet, 'cause inequalities andAblemishes in the finished product..A

construction that is'practically devoid of-all evenly toward the sheetsource. Y Practically none of the-glass. will, remain in the' tank for fthe rectangular furnace constructions, and there "willl be much lessreason or opportunity for the formation of devitrified glass.

i It is also an object of the invention to cause the glass which suplies-the sheet sourceto advance from the. rnace to the oint ofdrawat-.agreater velocity along yt e sides of the -flow than toward thecenter, whereby 'flow ofihthe upper strata-of the glass and cn'Vv edgesofthe draw-pot.

position until it becomes quite diierent fromv the main current. of4molten glass flowing .duction in 'the temperature o the furnacejatmosphereabove.- the glass, and the' 'tem'- The present-invention aimsto avoid these diiculties by providing a tapering tank the glasslowinginto the sheet from the rear .tank lfurnace, and more particularlyto such.

'or closed end of the draw-pot will be renewed from this excess flow of.glass at the sides ofthe pot; I

. Inconnection w'itlithe tapering or rof gressively narrowingv channel,through w rh 'the glass flows from the meltin ,tankfto Athe draw-peaapeculiarly -we gea-shapedl iioat isemployed at an intermediate point 1nthe channelf to lassist in regulating the force a faster and moreregular llowl along the sides'o` thetapered channel. `As a ful-f ther'ald-to this s ame'end, im elevated ridge or throttling member is builtinto thebottom ofthechannlfadjacentthe draw-pot, itsv 'principahfunction being to divert a1 greater quantity of the 'glass toward the'side .This tapered furnace lends itself toga gradual reduction in theheight and general dimensions ofthe heet'- ing 'chamber above `the.glass asv the flew ,-0,

ceedsy from' the meltingy tank to the source. This makes possible4a"'graduel Tre# peratu're of the glass 'will theA ro ssively reduced asit moves toward" the iw-pot. This' loss of `heat from` the glass willbe] gradual .and will impart. a' more uniform uidity, and'more homoeneous structuref to the flowin stream of p astio glass in the narroweran shallower vrtions of the ta-` permg channel, -and wil tend to preventcarrying along with the advancing glass any highly cated vein fromthe-melting end of the iurnace.4 The invention 'also comprises, 1naddition tof the progressively reduced cover arches, a system ofindeendently adplstable partitions or radiating s ieldsfor impedingthe flowof heated from, the melting and refining tanks to that portion of the taered- 'channel whichserves4 as l.' cooling c amber. The above andvother-'ob'ects and advantages of this invention wi be more clearlyunderstood from the following detailed description of one approvedform'of furnace embed in'g the principles' of this invention.

' In t e aceompanyin drawings:

Fig. 1 is a horizonta section through the enclosing chambers, showing aplan view of 'thegeneral tank eonistructign.-` This'sectionconstruction' also V cated in the drawin is taken substantially on theline 1--1 of F ig. 3 is a transverse vertical section takensubstantially on the line 3-3 of Fig. 2.

Fig. 4 is a transversevertical section through the draw-pot and theheating furnace therebeneath, this view being taken substantially on theline 4--4 of Fi 2.

Fig. 5 is a partial vertical centra section through `the draw-pot andits supports, taken substantially on the line 5-5 o 1.

Fig. 6 is a perspective view of e drawpot, the forward rtion of the potbein git away substantially on the lineH-- o e melting tank 1 is of theusual rectangular construction and the larger portion thereof is brokenlaway in the drawings, onl the rear end being illustrated, from whichthe glass flows through the refining and cooling chambers to the shallowdrawpot 2 from which the glass sheet is drawn upwardly. The molten glassis not indias its presence would cover up several o the importantfeatures ofY the furnace construction. However,-

the iloater 3, -and other features to be -described hereinafter, areshown in operative position as if the lass were resent in the tank. Thenorma by the broken line 4 in Figs. 2 and 3 ofthe drawings. Also theposition occupied by the glass sheet, when same is being drawn upwardlyfrom the pot 2, is indicated b the broken line 5 in Figs'. 1' and 2 ofthe raw- Lghe draw-pot 2 is of much the same rgeneral dimensions' as hasbeen customary in previous constructions, being somewhat wider than thewidth of Vthe sheet to be drawnl therefrom and relatively shallow so asto contain only a small quantit of molten or plastic lass as comparedwit the main portions o the furnace construction. Theglass in thisdraw-pot is maintained at the requisite temperature by a furnaceconstruction therebeneath as will ,be later described.-

7 is drawn vinto the sheet, it must ,be reto flow placed by molten glassfrom the furnace, lass hasA and in revious construction this neatli thesheet source to t e closed end 8 of the pot. One object of the resentinvention is to provide dee r side c annels 8 in the draw-pot and directthe greater portion of the molten lass flowing to the closed.- end ofthe pot -t rough these chanlass leve is indicated` 'well as by'thefriction offered by nels. This will be described more in detailhereinafter.

That portion of the furnace structure through which the molten glassflows from the melt tank 1 to the draw-pot 2, wherein the re and coolingo erations are carried out, 1s of a gradua l ta ring formation both inwidth and dept prises an upwardl sloping floor or bottom wall 9 andinwar ly sloping or converging side walls 10. The entrance to thistapering channel is preferably somewhat narrower and shallower than themelti pot itself, as indicated in Fi 1, 2 and. 3, ut of ccnsiderablygreater imensions than the width tccmand depth of the draw-pot 2. Theside walls 10 gradually converge from their junction with the rear wall11 of the melting tank until they join evenly with the side walls of thenarrower draw-pot 2. The floor 9 slopes up from its junction with thewall 11 of the melting chamber until it coincides with `the bottoms ofthe channels 8 leading into the draw-pot. The central floor 12 of thedraw-pot extends horizontally a short tance into the narrower end of thetapered channel and then slopes down at a steeper angleY as'indicated at13 until this slope merges with the oor 9. Thus a central ridge 'or'wedge is formed in the narrower portion vof the channel which acts as athrottling or retarding member for 4the glass fiowing through thecentral rtion, and tends to divert a portion oft 'sglass towards thedeeper edge rtions 14 of this channel. This unimp ahead at a greaterrate than t e central pored. lass will flow tions of the stream, intoand through the 'channels 8 to the rear end 7 of the draw-pot. I At anintermediate location in this ta red refining and cooling chamber, .theshaped float 3 is positioned. The of this float is wed 15 of the wedgepointed u cated in Figs. 1 to 3. e float is also ples iarly nt facege-shaped with the edge i ream as in wedge-shaped as to its bottomportion with f threatest thickness at the center, as indic ait 16 in.Figs 2 and 3. The ends of t e we 'by the locks-17 shdable through 'esides areenga ed and held in 'tion 1115,'

of the furnace chamber,A as indicated iiiv f F" 1.* e manner in whichthesurfacestrata of the molten this refining an cooling channel isgraphically illi'istratcd rows thereon in thev flowing glass enters thechannel, the side portions of the stream will be retarded -by t econverging sides of the channel as the side walls` 10, so thatthe'central portions will tend to advance as indicatedlb line a. efectwould continue and be come more pronounced as the glass advances lasswill advance through im; gy the broken lines with arl ig. 1 of thedrawings. As

down the channel were it not for the retarding influence of the wed-shaped iloat 3. The thicker central portlons of this float will retardthe glass flowing along the middle of the channel and force this centralglass to either flow under this deep lid central portion or ow towardthe sides of the channel Where there is a freer passage beneath theshallower ends of the lloat. The resulting effect on the advancin streamof glass is indicated by the broken ines b, e, d and e, which show thatthe side streams of glass gradually overcome their initial handicap andflow ahead through the less obstructed side portions of the channel.After the glass has passed beyond the oat 8, the central dow 1s furtherim ded by the throttling ridge 13 already described sothat more of themolten glass will be diverted toward the side rtions 14 of the channel,as indicated by t e broken lines f, and L. When this surface glassreaches t e drawpot 2, the central rtion of the` ilow will advancerather uni ormly toward the sheet, as indicated by the broken line t',but the deeper edge portions of the stream in the channels 8 will flowunder and around the ends et the sheet source to supply thebody oi'glass 7 in the closed end of the pot. This glass '7 will then be drawnback into the side of the sheet remote from the furnace, as indicated bythe arrows at the left-hand end ci Fig. 1. In this way, a substantiallyeven and uniform flow of molten glass is provided'- to both sides of thesheet source and no kets or dead corners are left in the refining orcooling portions of the furnacestructure where stagnant glass mayaccumulateand devitriy. Obviously, as the crcss-sectional area of theflowing stream of glass decreases, the speed of the stream mustincrease. This constantly increasin flowing speed as the draw-pot isapproached aletli prevents stagnation and its attendant evi Also, theupwardly -sloping'botto'm wall tl produces a constant Aupward movementof the lower strata of glass, whereas the float 3 and the throttlingridge 13 cause a downward and sideward movement of portionsof the upperstrata. This tends to give a form wardmg impulse to the entirecross-section et glass in the channel, and 4vthere-will be n replacing'il -drewt from glaismthe tan flaco portions.v

ow .movement toward the practically all substrata of aswell as from thesurills-the drifter refined glass proceeds toward the draw-pot along theta ring channel., there will be a constant ten ency for all acum orother lloating foreign particles to' be drawn4 toward the side walls 10of the tank because of the generally tapering con- "mruction of thechannel. This Heatingv material Awill be further diverted toward theside .Walls by the front wedge-shaped' face of the lioat 3, alreadydescribed. These surface im urities may be removed, by the ordinary s'mining process, through the o nings 18 in the side walls of the furnaceThe cover arches for the tapered refining and cooling portions of thetank are made progressively narrower and lowel as the tank narrows fromthe melting chamber toward the draw-pot. In the constructionillustrated, the chamber above that portion of the channel from themelting tank 1 to and somewhat beyond the float 3 consists of a pair ofspaced side walls .19 and a second pair of more closely positioned sidewalls 20, both the wider and narrower portions of this .chamber beincovered by a continuous cover arch21. Ighis portion of the tankcorresponds to what is known as the reiin' tank in installations now inuse. Beyon the side walls 20 is a thirdA air of still more closelypositionedside wa 1s 22 covered b a lower arch 23. This smaller r-` ition o the chamber encloses that end o the channel which corresponds tothe cooling tank in revious constructions. The rear end of the lass isdrawn into the openv draw-pot, is su ntially closed by any suitable formof blocks or gate members 24. In order to prevent excessive loss of heatfrom the glass 1n the open draw-pot, all of this glassexce t acomparatively narrow portion at eit er side o the sheet 5 is coveredover by a pair of lip-tiles 25, as in previous constructions such asshown for example in the Colburn patent noted above. For the sake Aiscooling chamber, from which of clearness in the drawings, theselip-tiles 25 havebeen omitted from the plan view Shown in 1o As shown inFigs., 2 and 3, one or preferably a series of vertically movable han ingpartition members 26j are'located in t e furnacechamber, preferably nearthe junction of the refining and 'cooling chambers. These partitionmembers ma be formed of suitable refractory materia and form a curtainto partly shut off the diminished .heating space at the deliver end ofthe .tapering furnace from the arger heating areas toward the meltingend of the fur- These partitions 26 are independent- Iy adjustablevertically and will usually be A4potioned somewhat as shown in Figs. 2

and 3, with the central `partition or partitions project-in v furtherdown into the chamber than t ose partitions nearer the sides of thechamber. In this way the cen-` tral members will impede the passage ofyheat waves toward the central body of glass in the cooling chamber, andwill reflect and radiate this heat back into the refining tank, whereasthe more open spaces beneath the partitions at', adjacentthe edges ofthe tank willipermit the free` passage -of heatover `the side portions14ofthe channel.

vmovin 'ing with the necessary temperature condi- Th'is heat will Araisethe tem rature ofthe glass adjacent'the'walls of t echanuel, and to agreat d reduce the. 'surface tension which ach; 'as a brakeor retardingagent algainst the free tlow of glass along the side c annels. Also byproperly adjusting the several partition members vertically, more. `orless heat may be permitted to act on the glass adjacent the drawt andthus in a w'ay make this portion o the lass furnace in ependent of theheat con 'tions existling in the melting-'end ofthe tank. In this way,it will be possible to accurately overn the temperature and fluidity ofthe g ass toward the sheet without interfertions in the meltin andrefiningtanks.

Itwill be noted rom Figs. 2,:4, and 6,

that the formation of the side channels 8 I in the iloor of the vdraw-poging, and making central supports w .ereby a larger portion t 2 rovdes acentral arched formation 1n the ttom of the pot, as shown more clearlyat 26 in Fig. 6. This will considerably strengthen the pot structurepractically eliminating sagible the use of fewer of the underside of thepot is left freely exposed to the. heating gases in the chamber` 27therebeneath. As shown in Figs. 2 and V5, the bottom rib 28 at the frontopen end of .the draw-.pot is supported upon the con- 'tiinuous backwall -29 of the heating chamber 27. `The rear closed end 6' of the pot.

n a series of arches or is supported u stools 30 in the eating chamber,which may be of any ap rovedv form and are here il- *lustrated as o thetype disclosed in my copending application, Serial Number y 593,- 885,filed vOctober 11, 1922. 'Beneath the side channels 8, at anintermediate point in the length of the pot is a pair of sidesupporting.l stools ,31,` which as shown in Fig. 4, wi ly at their upperen s as at 32 to leave as much ofthe pot bottom as possible exposed tothe heating gases.- :The'chamber 27 is heated by a senes of burners:33,' the heating gases passing in through ports 34,

. around and through the chamber 27 as in'- ity ofmovement of thereplacing current' alox the sides of the pot so as to provide a s'ciency of properly fluent glass at the preferabl be cutaway central- 1.

' may be caused dog-metal is generally -formed when the glass has becomelov.' in .sodium contents sources of the sheet edges as well as .a freesupply ofr glass to the closed end of the draw-pot be ond the sheet. 'Itshould be understood t at in the commonly used pot, having a uniformlyflat bottom surface, the glass advances with its greatest velocity.

along the central'portion of the pot, and

when this central current arrives at the sheet source its upper stratummust flare or fan outwardly toward the edges of the pot to supply .thedemands of the! sheet edges, while its substratum passes under the sheetsource to replace the lass drawn from the closed end of the pot. hiscauses various convolutions and irregular tensional strains "n the bodyof glass adjacent and beneath the sheet source which are believed toaffect the uniformity of the sheet itself .and sometimes result in awavy and striated sheet formation. By having these deep-` -er'A sidechannels pass to. and beyond the sheet source there will be a more freeand even flow of glass to the closed end of the pot, without requiringthe' substratum' -movemer'lt beneath the main body of the sheet. Therewill result a more parallel streamline advance of the glass from bothends of the draw-pot into the sheet source and. the resulting sheetformation will be more free from locally warpin tensional stresses thanis the case with t e flat-bottomed pot now in use. Also'the glassadjacent the sides of the pot will .be constantly i renewedand will havenochance to stagnatev andxdevitrify.

As a general proposition, constructing a yfurnace of this type whereinthe lass flows from the melting tank through t e tapered refining andcooling portions to the pot, will Ameanl a gleneral decrease in furnacedimenslons wit tion surface relative to the amount of lass aconsiderable increase in radin-1 los contained.y This decrease incapacity o the l tank is brought about through the elimination ofgthoseportions of .the present tanks which merely contain ractically dead orstagnantglass, so that t e effective capacity of the tank is in no waydiminished. Since the' `constructionof this tank necessitates a moreuniform and even ilow of all strata of the glass towardthe delivery end,.there'will resu t a more speedy. consumption in sheet form 'of all lassproduced .in 'the melting end of theY rnace, .thus large] eliminatingthe formation of dog-metaf anotherwise toughened lass, as far assuch-defects y tank conditions. 'This om prolon heating after it isrefined or clarified an from thereafter being to variable temperatureconditions.

Claims: a

exposed 1. Alcontinuous tank furnace *for supply- I ing molten glass tosheet-glass machmes,

vside walls of comprising a melting tank a relatively eet is drawn, anda refining and cooling tank connecting the melting tank and pot, the therefining tank converging progressively from the relatively largedelivery opening in the melting tank to the relatively narrow open endof the pot.

2. A continuous tank furnace for supply- .ing molten glass tosheet-glass machines,

comprising a melting tank, a relativel small and shallow pot from whichthe slieet is drawn, and a refining and cooling .tank connecting themelting tank and pot, the door of the refining tank sloping upwardlyfrom the relatively deep delivery opening in the melting tank, to therelatively shallow open end of the pot. l

3. A continuous tank furnace forsupplying molten glass to sheet-glassmachines, comprising a melting tank, a relatively small and shallow potfrom which the sheet is drawn, and a refining and cooling tankconnecting the melting tank and pot, the floor of the refining tanksloping upwardly from the relatively deep delivery opening in themelting tank, to the relatively shallow open end of the pot, and theside walls of the refining tank converging from the wide deliveryopening in the melting tank to the relatively narrow open end of thepot.

4. In a continuous tank furnace for suplying molten glass to sheet-glassmachines, including a relatively large and deep melting tank and arelatively small and shallow pot from which the sheet is drawn, aprogressively tapering refining and cooling tank through which themolten glass flows to the 5. In a continuous tank furnace for supplyingmolten glass to sheet-glass machines, including a relatively large anddeep melting tank and a relatively small and shallow pot from which thesheet is drawn, a progressively tapering refining and cooling tankthrough which the molten glass flows to the pot, having an elevatedcentral ridge adjacent its narrow delivery end for retarding the centraliow of glass and diverting a portion of the flow along the side walls ofthe tank.

6. In a continuous tank furnace for supplying molten glass tosheet-glass machines, including a relatively large and deep melting tankand a` relatively small and shallow pot from which the sheet is drawn, aprogressively tapering refining and cooling tank through which themolten glass flows to the pot, and a fioater projecting into the surfaceglass at an intermediate position in the taper tank, the central portionof the fioater being deeper than the end portions, whereby the centralfiow will be retarted and diverted along the side walls of the tank.

7. In a continuous tank furnace for supsmall plyinor molten glass tosheet-glass machines, including a relativel large and deep melting tankand a relatively small and shallow j p ot from which the sheet is drawn,a progressively tapering refining and cooling tank through lwhich themolten glass flows to the'.

pot, having an elevated central ridge adja-,

cent its narrow delivery end for vretarding the central flow of glass,and a ioater projecting into the surface glass at an intermediateposition in the tapered tank, they central portion of the floater beingdeeper.

than the end portions, whereby the central flow will be retarded anddiverted along the side walls of the tank. A

8: In a continuous tank furnace for supplying molten glass tosheet-glass machines,

including a relatively large and deep melting tank and a relativelysmall and shallowpot from which the sheet is drawn, a progressivelyVtapering refinin tank through which the m'o ten. glass-flows to thepot, and a fioater projecting into-the surface glass at an intermediateposition in the tapered tank, the central portion of the floater beingdeeper than the end portions, whereby the central flow will be retardedand diverted along the side walls of the tank, the front face of thefloater being wedgeshaped and pointing into the floating glass to divertfloating impurities toward the side walls of the tank.

9. In a continuous tank furnace for producing molten glass, comprising arefining tank, a fioater positioned in the surface glass in the refiningtank, the central portion of the floater projecting deeper into themolten glass than the end portions. l0. In a continuous tank furnace forproducing molten glass, comprising a refining tank, a floater positionedin the surface glass in the refining tank, the floater being 'wider anddeeper at its center than at the ends, whereby tarded at the center anddiverted toward the sides of the tank.

11. In a continuous tank furnace for sup-v plying molten glass to asheet glassy drawing machine, a shallow draw-pot from which the sheet isdrawn, havin a closed end and an open end through which the glass flowsin from the source of supply, there being relatively deep channelsadjacent the side walls of the -pot through which glass flows be- .yondthe sheet source to the closed end of the pot.

12. In a continuous tank furnace for supplying molten glass to a sheetglass drawin machine, a shallow draw-pot from whic the sheet is drawn,having a closed end and an open end through which the glass flows infrom the source of supply, therebeing deeper channels adjacent the sidewalls of the pot sloping upwardly from the open end till they merge withthe plot bottom beyond i,

and cooling v the sheet source, molten glass owing through thesechannels to replace that withdrawn from the closed end of the pot.

13. In a continuous tank furnace for supplying molten glass to a sheetglass drawing machlne, a shallow draw-pot from which the sheet is drawn,havin a closed end and an open end through which the glass flows in fromthe source of supply, and a tapered refining vtank through which themolten glass passes to and through the open end of the pot from thesource of supply, there being relatively deep channels adjacent the sideWalls of the tank and pot through which glass flows beyond the sheetsource to the closed end of the pot.

14. In a continuous tank furnace for supplying molten glass to a sheetglass drawmg machine, a shallow draw-pot from which the sheet is drawn,having a closed end and an open end through which the glass fiows infrom the source of supply, and a tapered refining tank through which themolten glass passes to and through the open end of the potfrom'thesource of supply2 there beingA relatively deep channels adjacentthe side walls of the tank and pot which slope upwardly'till they mergewiththe pot bottom beyond the sheet source, molten glass flowing throughthese channels to replace that withdrawn Vfromthe closed end of the 15.Ina continuous tank furnace for supplying molten glass to a sheet glassdraw lng machine, a shallow drawpot from which the sheet is drawmhavinga closed end and an open en'd through which the glasshfiows 1n from thesource of supply, there being rela tively deep channels adjacent thesidewalls of the pot through which glass flows beyond the-sheet source tothe closed end of the pot, a heating chamber beneath the pot, and potsupporting members withm the chamber beneath the channels, the archedvpot bottom between the channels being self-supporting. l

16. A continuous tank furnace, comprlsing a tapering refining andcooling tank, and a series of connecting chambers enclosing the tank,said chambers being progressively smaller from the wider to the narrowerend ofthe tank.

17. A continuous tank furnace, comprising a tapering refining andcooling tank,

a series of connecting chambers enclosing the tank, said chambers beingprogressively smaller from the wider to thenarrower end of the tank, andan adjustable hanging curtain in one of the chambers to regulate theflow of heating gases through the chambers.

18. A continuous tank furnace, compris ing` a tapering refining andcooling tank, a series of connecting chambers enclosin Athev tank, saidchambers being progresslvely smaller from the wider to the narrower endof the tank, and a hanging curtain in one of the chambers comprising aplurality of independently adjustable sections, to regulate the fiow ofheating gases through the chambers.

19. In a tank furnace `for producing molten glass, comprising arefiningtank and an enclosing chamber thereover, a hanging curtain in thechamberv comprising a plurality of independently adjustable sections, toregulate the flow of heating gases through the chamber.`

20. In the art of making sheet glass, the method which consists inadvancing a body of molten glass from the continuous melting tankportions of a furnace towards the drawpot from which the sheet of glassis drawn, 1n a manner to progressively and gradually reduce itscross-section.

21. In the arty of making sheet glass, the method which consists inadvancing a body of molten glass from the continuous melting tankportions of a furnace towards the drawfpot from which the sheet of glassis drawn, in a manner to progressively and 'gradually reduce itscross-section, while 'si multaneously acting on the body of glass toincrease the stream line movement towards the side areas thereof.

22. In the art ofmaking sheet glass, the method which consistsv inadvancing a body of molten glass'from the'melting end of a furnacethrough a horizontally tapering de-` of sheet-drawing tractive -forceand the force of gravity with progressively increasing velocity fromthe' melting end 'of the -furnace structure t the point ofsheetemergence in the draw;pot,"while progressively reducing the volume. ofheating atmosphere thereover and the tem 'erature of the moving vbody asits velocity is" 'eing increased.

24. In the art ofinaking' sheet glass, the method of clarifying'f'and'impartinglike plasticity to-abody'of refined glass while withdrawing a`sheet of glass therefrom,

which' consistsin' advancing a'body of refined glass from the vmeltingend of'a furnace structure toward'th'e point at which the sheet isdrawn, in a manner to gradually reduce itscross-section whileprogressivelyl-v, increasing its velo.c1ty,"and whilel concurrentlychanging its'state of-'fluiditji from' a liquid to a plastic consistencyas its crosssection is being reduced, and during said into a draw-potfrom which a sheet of glass-y is drawn, which consists in causing a flowmovement of molten glass along horizontal,

stratums in a manner to progressively reduce the cross-section of theflow and its volnine While hastening its movement, in progressivelylowering the temperature of the glass as its cross-section is beingreduced, and in causin floating impurities on the surface thereo to movetoward the opposite side areas of the flow.

current of molten glass through a movement of a relatively largediinens'ioned4 body of glass in the direction of the drawpot at. apredetermined distance from the melting zone in the body of glass,in-progessively reducing the dimensions of the while increasin the speedand Width of its movement an delivering the same into the` draw-pot withan approximately uniform velocity along a front practically as wide asthe draw-pot. 27. -In sheet glass making, the method of producingand.'equalizing How. movement l from a melting; tank to the point of sheetemergence'in the draw-pot, `which consists,

first in causing a larger cross-sectionof fiowcontinent and inclusivefrom predetermined 4stratums ofthe body of glass in the tank toward thedrawot, then in pro essively reducingthe width and depth o the `'How`While increasing its speed, and thereafterxin causing theadvancingevelocity to-v Ward' the sides ofthe flow to practically'equal' to the velocity at the center of the How as -it proceeds intothe' dravvot.

28. The method of ing velocity 'of a replacing stream movement kofmolten glass from a furnace into -a drawplot and toward a sheet's'ourceformation uner tractive drawing stress therein, which consists inretardingthe velocity of the ie-l placing glass along the main centralportion center of the replacing current of glass which is going into thepot, While relatively accelerating the substratum movement towards 'theside portions of the pot.

Signed at Toledo, and siate of ohio, this 28th day of February, 1923.,

y y ENocH rr. -FERGREN equalizing't e supplyinthe county of Lucas,l

:of its stream movement as said glass is ap- ,.proaching the4 draw-pot,while simultane- 26. The method of advancing a replacing'- urnace into adraw-pot, in which a sheet of glass is drawn, which consists in startinga slowvl l tebaseofa" 'drawn sheet formation, which consists in re-Atarding vthe substratum movement along the I 7o y l

